Methods for producing tomographic pictures with the aid of a number of X-ray sources arranged with an angular offset on a gantry are fundamentally generally known, the person skilled in the art also being aware here of the problem of the scattered radiation occurring owing to the plurality of X-ray tubes being used simultaneously. At present there are two basically different variants for compensating or correcting this intensively occurring scattered radiation, specifically on the one hand by using a phantom to estimate the scattered radiation occurring either by measurement or by calculation and subsequently correcting the detector data with the scattered radiation values during the actual scanning. On the other hand, it is also known to measure the scattered radiation by various measures during the actual measurement on the actual examination object, and to undertake appropriate corrections.
In the first mentioned variant, the use of a phantom, the problem keeps arising that the measurements on the phantom, can reproduce the reality only approximately, and thus that any exact data relating to the scattered radiation can scarcely be available. It is also respectively to be considered here that the bearing of the examination object, that is to say generally a patient, with phantom conditions can be undertaken exactly only with difficulty, or it is also possible that a patient is wearing prostheses or implants that lead more intensely to scattered radiation that, of course, are not present in a generally valid phantom.
There are also fundamental attempts to obtain information with reference to the scattered radiation present during the actual scanning of the patient with the aid of a number of focus/detector systems. However, there is a problem here that there is additionally generally a need to use a relatively high radiation dose, since it is scarcely possible to carry out a rapid change in the dose rate of the X-ray tubes used without changing the acceleration voltage, and thus measurements required briefly during scanning are carried out exclusively with a single tube, as a rule with a full dose rate. A relatively high dose rate is thereby used for measuring the scattered radiation.